Recording medium and recording system

ABSTRACT

Disclosed in this invention is a recording medium characterized by forming on the support a recording layer containing a metastable sensitive substance which is an intermediate product of a reaction between a first colorless or light-colored material containing the S atoms released by light irradiation and a second colorless or light-colored material which develops color as it is sulfurized by said S atoms.

This is a continuation of application Ser. No. 179,081, filed Aug. 18, 1980, abandoned.

This invention relates to a recording medium and a recording system capable of forming the color image by using a high-density pulsed light such as laser light of flashed light.

Various proposals have been made on the recording materials sensitive to the high-density energy light such as laser beams, and some of these materials have already been put to practical use, but any of these devices is not fully satisfactory. Among the laser-using recording materials disclosed to date in the fields of facsimile, video disc recorders, etc., are the dry metallized paper for using He-Ne gas laser, metal deposition film for using He-Ne gas laser or Ar gas laser and As-Te type amorphous deposition film. However, the dry metallized paper, although high in sensitivity, requires a heat developing step, while the metal deposition film involves the problems that the recording energy is high and the environment might be contaminated by the evaporated metal. Also, such film is unsuited as a recording medium for obtaining the visible images for hard copies, etc., because of the recording principle. Other methods are also envisaged, such as recording with high-output laser by using a heat-sensitive recording paper, but generally these conventional methods require the high-output laser light such as He-Ne gas laser, He-Cd gas laser and, in some cases, Ar laser, CO₂ laser, etc., and this has been an obstacle to the attempts for minuaturization of the device, cost reduction and other improvements.

The present invention has been deviced with the object of solving these problems, and it is intended to provide a recording medium which is suited for picture recording and which is high in light responsiveness and sensitivity and has little risk of environmental contamination, and a recording system using such recording medium.

In the drawings,

FIGS. 1, 2 and 3 show the spectral transmittances before and after exposure of the recording media according to this invention, said recording media using for its recording layer a Sb₂ Sb₃ -SnO system, a GeS₂ -SnO system and an In₂ S₃ -TeO₂ system, respectively, in the order of the figures.

FIG. 4 is a sectional view of a recording medium according to this invention, and

FIG. 5 is a diagrammatic drawing for illustrating the recording system according to this invention.

The invention is now described in detail while having reference to the accompanying drawings.

Described first is the recording system according to this invention. Firstly, a recording layer containing a metastable sensitive substance comprising a reaction intermediate product is formed on a support either by simultaneously depositing a first colorless or light-colored material containing the sulfur (S) atoms released by light irradiation and a second colorless or light-colored material, which develops color upon being sulfurized with the sulfur atoms, on the support from two material sources or by first mixing said both materials by using a binder and then coating the mixture on the support, and then this recording layer is irradiated with light in correspondence to the recording signal to dissociate the sulfur atoms from the first material and react the dissociated sulfur atoms with the second material to produce a colored sulfide to thereby record the recording signal.

The recording medium according to this invention comprises a recording layer provided on a support such as plastic, paper, glass, etc., said recording layer containing a sensitive substance which is in a metastable state and composed of an intermediate product of a reaction between a first material which releases the sulfur atoms upon light irradiation and a second material which develops color upon reaction with the sulfur atoms. As the first material, there may be used the organic sulfur compounds such as thiourea, thiosalicylic acid, thioacetaldehyde, thioformaldehyde, thiourethane, etc., metal sufides such as ZnS, Al₂ S₃, Sb₂ S₃, Sb₂ S₅, In₂ S₃, CdS, GaS, Ga₂ S₃, CoS, Ag₂ S, HgS, SnS, SnS₂, SeS, Tl₂ S, Tl₂ S₃, FeS, Cu₂ S, CuS, Na₂ S, PbS, NiS, Bi₂ S₃, MoS, MoS₂, TiS₂, P₂ S₅, MnS, CrS, etc., or sulfur in its single form. Among them, the metal sulfides are excellent because of relatively easy deposition and high recording sensitivity, and especially Sb₂ S₃, In₂ S₃, Ag₂ S, SnS, SnS₂, Bi₂ S₃, ZnS, GeS and GeS₂ can give a light-colored high-sensitivity recording layer. Particularly, Sb₂ S₃, InS₃, GeS₂ and Bi₂ S₃ show the excellent properties.

As the second material, there may be used the metals such as Pb, Bi, Ag, Sn, Sb, Te, Se, Cu, Mg, Sc, Y, Ti, Cd, Zn, In, Si, Ge, As, Al, Ga, Cr, Mn, Fe, etc., metal oxides such as ZnO, Sb₂ O₃, In₂ O, InO, In₂ O₃, OsO₄, CdO, Ga₂ O, Ga₂ O₃, Ag₂ O, Co₂ O₃, MoO₃, SnO, SnO₂, Tl₂ O, WO₃, Bi₂ O₃, TeO₂, PbO, Pb₃ O₄, PbO₂, Nb₂ O₅, V₂ O₅, Ni₂ O₃, etc., metal halides such as PbI₂, BiI₃, AgI, SnI₂, SnI₄, SbI₃, CuI, ZnI₂, AlI₃, InBr, etc., or organic metal salts such as lead acetate, zinc acetate, lead oxalate, zinc oxalate, silver acetate, silver oxalate, lead citrate, silver citrate, zinc citrate, etc. Among them, the metal oxides are excellent in that they can provide a high-sensitivity light-colored recording layer, and especially SnO, TeO₂, Pb.sub. 3 O₄, Bi₂ O₃, In₂ O₃, Tl₂ O₃, Tl₂ O, Sb₂ O₃, MoO₃ and Ag₂ O show the excellent properties.

As the binder used in case of forming the recording layer by coating, there may be employed nitrocellulose. PVA (polyvinyl alcohol), polyvinyl acetate, polyacrylic acid ester or the like diluted with a suitable solvent such as acetone, ethanol, etc. In case of forming the recording layer by means of deposition, it is possible to employ the sputtering technique. The degree of vacuum used for the deposition operation including sputtering may be around 10⁻⁵ Torr, and as for the thickness of the recording layer, sufficient contrast can be obtained by providing such thickness of around 1,000-2,000 A.

The invention is described in further detail hereinbelow by way of the examples thereof.

EXAMPLE 1

Metail sulfides and metal oxides were simultaneously deposited from the separate sources on a polyester support 3 having the thickness of 35μ under the deposition vacuum degree of 5×10⁻⁵ Torr to form the recording media containing the materials such as shown in the left-side columns in Table 1 and having a recording layer 4 with a thickness of 1,000-2,000 A as shown in FIG. 4. By exposing the recording layer 4 of each recording medium to Xe flashed light, there were obtained the results such as shown in the right-side columns in Table 1. FIGS. 1-3 show the spectral transmittance curves (before and after exposure) of the recording media obtained in the manner described above. FIG. 1 shows the spectral transmittance curves of the recording medium having its recording layer composed of Sb₂ S₃ -SnO, FIG. 2 shows those of the recording medium having a GeS₂ -SnO recording layer, and FIG. 3 shows those of the recording medium having an In₂ S₃ -TeO₂ recording layer, and in each figure, the solid line 1 shows the spectral transmittance before exposure and the broken line 2 shows the spectral transmittance after exposure.

                                      TABLE 1                                      __________________________________________________________________________                                 Record-                                                                        ing                                                   First                                                                               Second                                                                              Color before                                                                           Color after                                                                           energy                                             No.                                                                               material                                                                            material                                                                            exposure                                                                               exposure                                                                              (mj/cm.sup.2)                                                                       Characteristics                               __________________________________________________________________________     1  Sb.sub.2 S.sub.3                                                                    SnO  Light-yellow                                                                           Brown  36   High sensitivity,                                                              high contrast                                 2  "    TeO.sub.2                                                                           Light-brown                                                                            Black  112  High sensitivity,                                                              high contrast                                 3  "    Bi.sub.2 O.sub.3                                                                    Light-yellow                                                                           Light pink                                                                            160                                                4  "    Tl.sub.2 O.sub.3                                                                    Light-yellow                                                                           Gray   76   High sensitivity                              5  "    Sb.sub.2 O.sub.3                                                                    Light-yellow                                                                           Gray   36   "                                             6  GeS.sub.2                                                                           SnO  Light-yellow                                                                           Dark brown                                                                            120  High sensitivity,                                                              high contrast                                 7  "    TeO.sub.2                                                                           Light-brown                                                                            Black  160  High contrast                                 8  "    MoO.sub.3                                                                           Light-yellowish                                                                        Brown  84   High sensitivity                                           green                                                             9  "    Tl.sub.2 O.sub.3                                                                    Light-yellow                                                                           Yellowish                                                                             76   "                                                                  white                                                     10 "    Pb.sub.3 O.sub.4                                                                    Light-yellowish                                                                        Brown  60   "                                                          brown                                                             11 In.sub.2 S.sub.3                                                                    TeO.sub.2                                                                           Light-yellowish                                                                        Black  160  High contrast                                              brown                                                             12 "    Pb.sub.3 O.sub.4                                                                    Light-orange                                                                           Black  280  "                                             13 "    In.sub.2 O.sub.3                                                                    Light-yellow                                                                           Light brown                                                                           160  "                                             14 "    Tl.sub.2 O.sub.3                                                                    Light-yellowish                                                                        Brown  160                                                             brown                                                             15 "    Ag.sub.2 O                                                                          Light-yellowish                                                                        Orange 84   High sensitivity                                           brown                                                             __________________________________________________________________________

There was also similarly prepared the recording media by using ZnS, Bi₂ S₃ and SnS₂ as the first material and ZnO, PbO, CdO, etc., as the second material, and the similar effects were confirmed.

EXAMPLE 2

The recording media were produced after the manner of Example 1 by using thiourea as the first material and various types of sulfides as the second material, obtaining the results shown in Table 2.

                                      TABLE 2                                      __________________________________________________________________________                                  Record-                                                                        ing                                                  First                                                                               Second                                                                              Color before                                                                            Color after                                                                           energy                                            No.                                                                               material                                                                            material                                                                            exposure exposure                                                                              (mj/cm.sup.2)                                                                       Characteristics                              __________________________________________________________________________     1  Thiourea                                                                            Bi   Light-brown                                                                             Deep brown                                                                            120  High sensitivity,                                                              high contrast                                2  "    Pb   Brown    Black   84  High sensitivity                             3  "    Ag   Yellowish brown                                                                         Grayish                                                                                76  "                                                                  black                                                    4  "    Cu   Light-green                                                                             Grayish                                                                               160                                                                     green                                                    5  "    Sb   Grayish brown                                                                           Deep brown                                                                            120  High sensitivity                             6  "    Bi.sub.2 O.sub.3                                                                    Brown    Dark brown                                                                            152  High contrast                                7  "    SnO  Yellowish brown                                                                         Black  160  "                                            8  "    TeO.sub.2                                                                           Brown    Black  160  "                                            9  "    Tl.sub.2 O.sub.3                                                                    Light-brown                                                                             Grayish                                                                               120  High sensitivity                                                   black                                                    10 Thiourea                                                                            MoO.sub.3                                                                           Light-blue                                                                              Dark green                                                                            160  Specific color                                                                 tone                                         11 "    CuI  Light-brown                                                                             Deep brown                                                                            196                                               12 "    PbI.sub.2                                                                           Light-yellow                                                                            Yellow 358                                               13 "    AgI  Light-yellow                                                                            Yellow 508                                               14 "    Lead Brown    Grayish                                                                               120  High sensitivity                                     silicate      black                                                    15 "    Lead Brown    Black  280                                                       acetate                                                                __________________________________________________________________________

There were similarly prepared the recording media by using Se, Te, PbO, Ag₂ O, Pb₃ O₄, PbO₂, SnI₂, bI₃, BiI₃, SnI₄, etc., as the second material, and the similar effect of the products was confirmed.

EXAMPLE 3

The semiconductor laser light with an output of 10 W, wavelength of 904 nm, duty factor of 0.1% and pulse duration of 200 n sec., rectified into the beams of 200μ×10μ, was applied to the recording media obtained in Examples 1 and 2 as shown in FIG. 5, obtaining the results shown in Table 3.

In FIG. 5, numeral 5 indicates a semiconductor laser diode which emits laser light 5', 6 a condensing lens, 7 a galvano-mirror, 8 the scanning section, 9 and 9' rolls for feeding and taking up the recording medium 10, and 11 the area of the recording medium 10 exposed to the laser light.

                  TABLE 3                                                          ______________________________________                                                                       Writing by                                              First         Second   semiconduc-                                      No.    material      material tor laser                                        ______________________________________                                         1      Sb.sub.2 S.sub.3                                                                             SnO      Δ                                          2      "             TeO.sub.2                                                                               O                                                3      "             Sb.sub.2 O.sub.3                                                                        O                                                4      "             Pb.sub.3 O.sub.4                                                                        O                                                5      GeS.sub.2     SnO      Δ                                          6      "             TeO.sub.2                                                                               O                                                7      "             MoO.sub.3                                                                               O                                                8      "             Pb.sub.3 O.sub.4                                                                        O                                                9      "             Tl.sub.2 O.sub.3                                                                        O                                                10     Bi.sub.2 S.sub.3                                                                             Tl.sub.2 O.sub.3                                                                        O                                                11     In.sub.2 S.sub.3                                                                             SnO      X                                                12     "             TeO.sub.2                                                                               O                                                13     "             In.sub.2 O.sub.3                                                                        Δ                                          14     "             Ag.sub.2 O                                                                              O                                                15     "             Pb.sub.3 O.sub.4                                                                        X                                                16     SnS.sub.2     MoO.sub.3                                                                               O                                                17     Thiourea      Ag       Δ                                          18     "             Pb       Δ                                          19     "             PbI.sub.2                                                                               X                                                20     "             Lead     O                                                                     silicate                                                  ______________________________________                                          (Note)                                                                         O: Easy to write.                                                              Δ: Slightly difficult to write.                                          X: Unable to write.                                                      

EXAMPLE 4

1 g of nitrocellulose was well dissolved in a mixed solution of acetone and n-butyl alcohol (mixed in the ratio of 2.5 cc of acetone to 1 cc of n-butyl alcohol) to form a binder, and 1 g of Sb₂ S₃ and 1 g of SnO were added to 100 cc of said binder, and the mixture was crushed and mixed up in a ball mill for about 1 hour to obtain a viscous solution. By using this viscous solution, there was formed a recording layer having the thickness of about 2μ on a paper base having the thickness of about 70μ by a spinner. When this recording layer was irradiated with semiconductor laser light in the same way as in Example 3, the recording layer of gray in color was changed into brown in color.

EXAMPLE 5

A recording layer was formed similar to that prepared in Example 4 by using In₂ S₃ and TeO₂ and irradiated likewise with semiconductor laser light, whereby the recording layer of gray in color was changed into dark brown in color.

As described above, the present invention enables recording by low-output light such as semiconductor laser light or flashed light and can realize minuaturization of the device and cost reduction in adaptation to the various devices such as facsimile, CRT, hard copying machine, etc.

Further, since this invention employs a sulfurization reaction which is generally well-known for its excellent light responsiveness, the device of this invention is suited for picture recording using high-density pulse light, high in recording sensitivity and in recorded picture quality and free of any risk of environmental contamination. Thus, it is expected that this invention will display its splended characteristics in adaptation in the field of optical information recording or visible picture recording.

It is to be particularly noted that when forming the recording layer containing a sensitive composition by simultaneously depositing the basal materials from the multiple deposition sources, the reaction between the two materials is advanced partly to bring the sensitive composition into a metastable state to increase the recording sensitivity. This is considered due to an action of the sulfurization reaction which is completely different from the hitherto conceived one.

Also, in the case of coating, it is possible to obtain a recording medium with excellent stability and color tone in particular by properly selecting the binder as well as the first and second materials. 

What is claimed is:
 1. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal, for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being selected from the group consisting of Sb₂ S₃, In₂ S₃, ZnS, GeS, GeS₂, SnS, SnS₂, Ag₂ S, and Bi₂ S₃, said second material being selected from the group consisting of SnO, TeO₂, Pb₃ O₄, Bi₂ O₃, In₂ O₃, Tl₂ O₃, Sb₂ O₃, MoO₃ and Ag₂ O, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, and said dissociated sulfur atoms react with said second material to produce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 2. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being selected from the group consisting of Sb₂ S₃, In₂ S₃, GeS₂ and Bi₂ S₃, said second material being selected from the group consisting of SnO, TeO₂, Pb₃ O₄, Bi₂ O₃, In₂ O₃, Tl₂ O₃, Tl₂ O, Sb₂ O₃, MoO₃ and Ag₂ O, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, and said dissociated sulfur atoms react with said second material to produce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 3. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being Sb₂ S₃, said second material being selected from the group consisting of TeO₂, Sb₂ O₃ and Pb₃ O₄, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, and said dissociated sulfur atoms react with said second material to produce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 4. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being GeS₂, said second material being selected from the group consisting of TeO₂, MoO₃, Pb₃ O₄ and Tl₂ O₃, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, and said dissociated sulfur atoms react with said second material to produce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 5. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by the high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being Bi₂ S₃, said second material being Tl₂ O₃, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, said dissociated sulfur atoms react with said second material to produce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 6. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being In₂ S₃, said second material being selected from the group consisting of TeO₂ and Ag₂ O, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, and said dissociated sulfur atoms react with said second material to roduce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 7. A recording medium adapted to be irradiated with high-density pulsed light in response to a recording signal for recording a visible image, comprising a support, a recording layer formed on said support, said recording layer containing at least a metastable substance composed of an intermediate product of the reaction of a first colorless or light-colored material containing sulfur atoms and a second colorless or light-colored material which develops color upon being sulfurized, the sulfur atoms in said first material being released by high-density pulsed light irradiation and said second material being sulfurized by said released sulfur atoms, said first material being SnS₂, said second material being MoO₃, said first and second materials being reacted such that the reaction advances partly to form said metastable substance, whereby when said metastable substance in said recording layer is irradiated with the high-density pulsed light corresponding to a recording signal, sulfur atoms are dissociated from said first material in the irradiated part of the recording layer, said dissociated sulfur atoms react with said second material to produce a colored sulfide to record the recording signal as a visible image directly on the recording medium in response to the high-density pulsed light irradiation.
 8. The recording medium according to claim 1, 2, 3, 4, 5, 6 or 7, wherein said metastable substance is produced by substantially simultaneous deposition of the first material and the second material.
 9. The recording medium according to claim 8, wherein said deposition is carried out by sputtering.
 10. The recording medium according to claim 8, wherein said deposition is carried out under a vacuum of substantially 10⁻⁵ Torr and said recording layer is substantially 1000-2000 A thick.
 11. The recording medium according to claim 1, 2, 3, 4, 5, 6 or 7, wherein said recording layer includes a binding material, the recording layer being formed by mixing said first and second materials by using said binding material and then coating the mixed materials on said support.
 12. The recording medium according to claim 11, wherein said binding material includes at least one material selected from the group consisting of nitrocellulose, polyvinyl alcohol, polyvinyl acetate and polyacrylic acid ester. 